Current Research About Twin to Twin Transfusion Syndrome
Twin-to-twin transfusion syndrome: a subset of the twin oligohydramnios-polyhydramnios sequence
Bruner JP, Rosemond RL
American Journal of Obstetrics & Gynecology. 169(4):925-30, 1993 Oct.
Objective: Our purpose was to assess the adequacy of currently accepted criteria for the diagnosis of twin-to-twin transfusion syndrome.
Study Design: Between April 1991 and February 1992 nine consecutive women with twin gestations and ultrasonographic findings of marked growth discordance, coexistent oligohydramnios-polyhydramnios, monochorionic placenta, and same sex of the fetus in the second trimester were evaluated. Mean gestation age at diagnosis was 19 weeks 5 days +/- 5 weeks, and mean growth discordance was 34% +/- 9%. Seven women underwent attempted sequential amniocentesis and cordocentesis at 23 weeks 6 days +/- 2 weeks 4 days to obtain amniotic fluid and cord blood from each fetus. Type O negative, leucocyte-poor, washed adult red blood cells were transfused into the small, oligohydramnic twin during cordocentesis; immediately afterward blood from the polyhydramnic twin was tested with the Kleihauer-Betke stain.
Results: The combined procedure was successful in six (86%) of the cases attempted. True twin to twin transfusion was confirmed in only four (44%) of those initially identified by ultrasonographic criteria. Hemoglobin difference > 5 g/dl was present in only one of the four cases, and in this case the recipient was anemic.
Conclusions: Currently accepted criteria are insufficient for the diagnosis of true twin-to-twin transfusion. Ultrasonographic findings of marked growth discordance, coexistent oligohydramnios-polyhydramnios, monochorionic placenta, and same sex identify the twin oligohydramnios-polyhydramnios sequence.
Bruner JP, Anderson TL, Rosemond RL
Placenta (1998) 19:81-86
Currently accepted sonographic criteria for antenatal diagnosis of twin-twin transfusion (TTT) syndrome include a monochorionic placenta with same-sex twins, marked growth discordance, and oligohydramnios of the growth-retarded twin with coexistent polyhydramnios of the larger twin. Our previous report of nine women fulfilling these criterion, examined using sequential funipuncture of both fetuses, demonstrated intertwin blood transfusion in only four cases (44%). We proposed that traditional sonographic criteria actually described a heterogeneous group of disorders more appropriately described as the twin oligohydramnios-polyhydramnios sequence (TOPS). We maintain that true TTT is a subset of this population, the antenatal diagnosis of which requires specific demonstration of transfusion from one fetus (donor) to the other (recipient). In this report, we have correlated antenatal placental evaluation using duplex pulsed wave Doppler analysis of arterial blood flow velocity with postpartum gross and histopathologic evaluation of the placenta, with special attention to microvasculature. We observed a higher incidence of resistance to blood flow, abnormal umbilical cord insertion, and diminished placental microvasculature. associated with oligohydramnic growth-retarded (donor) twins when compared with polyhydramnic (recipient) twins. Based on these observations, we purport that TTT and TOPS represent asymmetric placental insufficiency resulting from aberrant placentation.
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